JavaScript implements the method of dynamically importing static resource files such as js and css

/**
  * Dynamically import static resource files js/css
  */
var $import = function(){
  return function(rId, res, callback){
    if(res && 'string' == typeof res){
      if(rId){
        if($($('#' + rId), $('head')).length>0){
          return;
        }
      }
      //Load the resource file      var sType = (('.') + 1);
      // Support js/css      if(sType && ('js' == sType || 'css' == sType)){
        var isScript = (sType == 'js');
        var tag = isScript ? 'script' : 'link';
        var head = ('head')[0];
        // Create node        var linkScript = (tag);
         = isScript ? 'text/javascript' : 'text/css';
         = 'UTF-8';
        if(!isScript){
           = 'stylesheet';
        }
        isScript ?  = res :  = res;
        if(callback && 'function' == typeof callback){
          if (){
            ('load', function(){
              ();
            }, false);
          } else if () {
            ('onreadystatechange', function(){
              var target = ;
              if ( == 'complete') {
                ();
              }
            });
          }
        }
        (linkScript);
      }
    }
  };
}();